Additive manufacturing (AM) or three-dimensional printing has a special strategic position in the global competition. Therefore, the leading countries have been devoting efforts to develop such technology, so as to make improvement from the conventional manufacturing condition and enhance the advantages in global competition. The conventional additive manufacturing technology mainly focuses on the technology of laser additive manufacturing. The technology of laser additive manufacturing makes use the principle of laser melting, divides an item into layers of two-dimensional geometric figures according to a three-dimensional model, forms a powder layer by using a layering device, focuses a laser beam on the powder layer, performs a melt forming process according to the two-dimensional figure as required, and then sequentially stacks the layers into a three-dimensional product. In this way, a complicated structure that cannot be manufactured by using the conventional processing techniques can be accomplished.
However, the laser additive manufacturing technology faces the challenges of having a low production efficiency, needing improvement on the product quality, having difficulties to guarantee the stability of production, having only limited types of metal materials, and having difficulties to reduce the cost of materials and facilities, etc. One of the reasons why the product quality is degraded is that slag and oxides produced during the process of additive manufacturing fall back to a processing area where the melt forming process is not performed, making the product contains impurities and oxides.
Based on the above, the technology of additive manufacturing capable of preventing slag and oxides from falling back to the processing area where the melt forming process is not performed is certainly needed to improve the forming quality and stability of additive manufacturing.